In the past, combustible gas detector circuits have been devised comprising a bridge circuit containing, as one of its four impedances, a heated combustible gas detector. Such detector circuits are described, for example, in U.S. Pat. No. 4,317,796 and British Pat. No. 2,091,882. The resistive gas detector, whose resistance is temperature dependent, comprises a catalyst that promotes combustion of combustible gases, thereby providing additional heat to the detector. A variety of such detectors are known and used including, for example, a coil of platinum wire whose surface has been activated to combust hydrocarbons or the bead-type detector described in U.S. Pat. No. 3,092,799, suitably comprising a platinum wire coil embedded in a bead incorporating a combustion catalyst. The resistance of a detector of this type will change in response to changes in sample gas humidity and thermal conductivity. While it is possible to provide a dynamic compensator element in series with the detector in one leg of the bridge to provide correction for changes in sample gas humidity and thermal conductivity, most circuits of this type encounter hysteresis problems. That is, the presence of two dynamic elements in one leg of the bridge circuit (i.e., the compensator and detector) induces opposite and confusing signals to the circuit element resulting in hysteresis effects. For this reason, most constant temperature sensors substitute a fixed resistor for the compensator element, thus sacrificing correction for humidity and thermal conductivity changes. Most prior art catalytic combustible gas detectors of this type utilize conventional Wheatstone bridge circuits which are normally powered at either constant voltage or constant current. In either case, response time is relatively slow.